What optimization does move semantics provide if we already have RVO?

Question

As far as I understand one of the purposes of adding move semantics is to optimize code by calling special constructor for copying \"temporary\" objects. For example, in th

Answer 1

This line calls the first constructor.

stuff a(5),b(7);

Plus operator is called using explicit common lvalue references.

stuff c = a + b;

Inside operator overload method, you have no copy constructor called. Again, the first constructor is called only.

stuff g(lhs.x+rhs.x);

assigment is made with RVO, so no copy is need. NO copy from returned object to 'c' is need.

stuff c = a+b;

Due no std::cout reference, compiler take care about your c value is never used. Then, whole program is stripped out, resulting in a empty program.